Research On Atomic Force Microscope Integrated Dual-Probe Drive Device And Control Method

Atomic force microscope(AFM),an essential technical tool in micro-nano science,it has been carried on the large-scale commercialization in the society at present for its simplicity of operator,wide range of applications and high practicability.However,the traditional AFM single-probe system requires dual-probe to compensate for the reason that it cannot meet the increasing demand of measurement.For instance,in the process of high-resolution imaging,a wide range of coarse scanning imaging is usually performed by using a probe with a relatively thicker tip(the tip radius is about 10 nm to 1 micron)to find the approximate location of the target and then a smaller scanning range is used for high-resolution imaging with a finer tip(the tip radius is about 1 nm to 10 nm).In this paper,on the premise of the new AFM system research and development,through the finite element modeling and simulation platform COMSOL Multiphysics software of single probe the property of the beam parameters and the working process of the modeling simulation,according to the result to design reasonable integration design of dual-probe(including body size and structure,etc.),analysis of the integration of two dual-probe cantilever beam independence movement driven approach,at the same time analysis the dual-probe drives(probe holder)structure,reasonable design,and in the Solid Works software environment to develop the most appropriate mechanical design drawings.On this basis,various means and techniques are used to process the conceptual drawings in real objects,and the driving part of the integrated dual-probe is finally completed.Simultaneously,in order to realize the fast in-situ switching control of the integrated dualprobe,a voltage-displacement calibration method of piezo with the feedforward-feedback control method were proposed for the existing new AFM system to ensure the two independent cantilever beam armies worked within the effective Z-direction driving range during the switching process of the integrated dual-probe.PID control algorithm is used to ensure the spot is always in the center on the PSD when switching the cantilever beam of two probes,and the control method of secondary scanning alignment and Local Scan is used to realize the needle tip above the sample at the same position during the switching of the cantilever beam of two probes,so as to achieve the effective and accurate control effect of the integrated dual-probe scanning processing.SEM was used to conduct optical imaging experiments on the integrated dual-probe after MEMS processing and then actual structure was observed;the voltage-displacement and frequency-displacement curve of piezo were achieved by controlling any variable in voltage and frequency,for accurately calibrating piezo;Dynamic analysis and coupling analysis of two independent moving cantilever beams with an integrated dual-probe are performed respectively to ensure the accuracy of subsequent results;Finally,an integrated dual-probe driving device and a new AFM system were used to scan and image the samples.